ELN-441958 was developed by Elan pharmaceutical as a novel small molecule bradykinin B1 receptor antagonist against pain.

Nafadotride is a highly potent and competitive dopamine D3 receptor antagonist (D3DR), with efficacy against D2DR and D4DR as well. Nafadotride displayed a high affinity for dopamine D2 and D3 receptors, but a low affinity for doparnine D1 and D4. At dopamine D2 and D3 receptors, the potency was concentrated on the l-enantiomer, which was 7 and 20 times, respectively, more potent than the d-enantiomer. dl-Nafadotride, l-nafadotride and d-nafadotride were 6, 10 and 2 times, respectively, more potent at dopamine D3 than at D2 receptors. As compared to haloperidol, a D 2 receptor preferring antipsychotic, the behavioral profile of nafadotride is characterized by stimulant properties on locomotor activity of rats habituated to their environment occurring at low dosage, i.e. in the range of 1 mg/kg. In contrast, nafadotride exerts typical D 2 receptor blocking responses at much higher dosage: for instance, about 100-fold higher dosages were required to observe extrapyramidal effects like catalepsy.

GR 103691 is an effective and selective receptor antagonist of the D3DR (dopamine D3 receptor). GR 103691 was shown to have 100-fold higher selectivity for D3DR (dopamine D3 receptor) over the D2DR (dopamine D2 receptor) and D4DR (dopamine D4 receptor) sites. GR 103,691 is functionally active in vivo and will inhibit the hyperactivity response induced by intra-VTA (ventral tegmental area) injection of muscimol in rats.

BRL-15572 is a 5-HT1D receptor antagonist with pKi of 7.9, also shows a considerable affinity at 5-HT1A and 5-HT2B receptors, exhibiting 60-fold selectivity over 5-HT1B receptor.

AMG-9810, is a TRPV1 (vanilloid receptor 1) antagonist which blocks all known modes of TRPV1 activation, including heat, proton, and endogenous ligand activation. TRPV1 is a membrane-bound cation channel in peripheral sensory neurons. Inhibition of this receptor has been noted to cause anti-inflammatory effects. In murine dorsal root ganglion primary neuron studies, this compound has been shown to block capsaicin-evoked depolarization and calcitonin gene-related peptide release. Screening of AMG 9810 against a panel of G protein-coupled receptors and ion channels indicated selectivity toward TRPV1. In vivo, AMG-9810 is effective at preventing capsaicin-induced eye wiping in a dose-dependent manner, and it reverses thermal and mechanical hyperalgesia in a model of inflammatory pain induced by intraplantar injection of complete Freund's adjuvant. AMG-9810 is the first cinnamide TRPV1 antagonist reported to block capsaicin-induced eye wiping behavior and reverse hyperalgesia in an animal model of inflammatory pain.

AMG-487 is a potent and selective orally bioavailable chemokine (C-X-C motif) receptor 3 (CXCR3) antagonist that displays dose- and time-dependent pharmacokinetics in human subjects after multiple oral dosing. AMG-487 is an 8-azaquinazolinone, it can prevent the chemokines I-IP-10 and I-ITAC from binding to CXCR3. The preclinical properties of AMG487 has been extensively studied. The compound displays a greater than 1000-fold selectivity for CXCR3 versus a panel of other receptors, including 11 chemokine receptors. The safety profile of AMG487, as assessed by various genotoxicity and cardiotoxicity assays, revealed no major concerns. The ability of AMG487 to inhibit inflammatory cell migration in vivo was confirmed in a mouse model of bleomycin-induced cellular recruitment, where AMG487 significantly reduced infiltration of macrophages and lymphocytes into the lungs in CXCR3-KO mice. In a mouse model for idiopathic pneumonia syndrome (IPS), AMG487 reduced recruitment of donor T cells to the lung after allogeneic stem cell transplantation, leading to improved survival rates. Likewise, reductions in inflammation, pannus formation, and cartilage damage were observed upon administering AMG487. The preclinical studies convincingly paved the way for clinical studies on two inflammation-related diseases: psoriasis and rheumatoid arthritis. In 2003, results of a Phase I trial on AMG487 were disclosed. The compound was assessed for safety and pharmacokinetics in 30 healthy males in a randomised, double blind, placebo-controlled dose-escalation study. Generally, the compound was well tolerated and adverse events were mild to moderate. Disappointingly, no significant differences in the endpoints (psoriasis severity index or physician global assessment scores) were seen between patient groups. AMG-487 progressed to Phase II clinical trials but has been withdrawn because of lack of efficacy.

JNJ-17203212 is an TRPV1 receptor antagonist. The drug exerts potent antinociceptive and antitussive actions. JNJ-17203212 is developing by Johnson & Johnson for the treatment of pain and cough. No development reported.